The thermal tolerances of rolling element bearings are commonly determined by the material temperature limitations of the bearing rings or races. Bearings containing races fabricated from wrought or sintered superalloys may be capable of sustained operation at significantly elevated temperatures exceeding 800° F. (˜427° C.) and, in certain instances, approaching 1200° F. (˜648° C.). At still higher temperatures, however, the hot hardness and other desired physical properties of the bearing races rapidly diminish. It may be possible to enhance the temperature capabilities of a rolling element bearing by fabricating the bearing races from ceramic materials. Bearing races produced from ceramic materials are, however, relatively brittle and thus prone to fracture when subjected to significant mechanical loading. The propensity of ceramic bearing races to fracture when subject to loading can be particularly problematic when the rolling element bearing is mounted around a shaft fabricated from an alloy having a relatively high coefficient of thermal expansion as compared to bearing and, specifically, as compared to the inner bearing race. Consequently, few if any rolling element bearings presently exist that are capable of providing prolonged, reliable operation when subject to heavy loads at highly elevated temperatures exceeding 1200° F. (˜648° C.). While immaterial in the vast majority of applications, such temperature limitations can be unduly restrictive in instances wherein the rolling element bearing is utilized within certain types of high temperature devices, such as gas turbine engine bleed valves.
There thus exists an ongoing demand for rolling element bearings and other bearings capable of sustained, reliable operation at highly elevated temperatures exceeding 1200° F. (˜648° C.) and possibly approach or exceeding 1400° F. (˜760° C.). More specifically, it would be desirable to provide high temperature bearing races and other bearing components capable of maintaining relatively high hardness levels (e.g., Rockwell hardnesses of C50 or greater) under such highly elevated operating temperatures, while further remaining relatively resistant to wear, fatigue, and fracture in the presence of significant mechanical loading. It would also be desirable to provide efficient, cost-effective methods for manufacturing such high temperature bearing components. Other desirable features and characteristics of embodiments of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying drawings and the foregoing Background.